an odd query (because I'm like that...!). If a mains cable has been 'nicked' (cut a bit, not stolen), so that the casing is damaged, does that impair the cable's performance?
I had some rendering work done on an old house and the builders nicked the Sky cable. Water got into the nick and the box went 'boom'. Otherwise some tape will do the job, but ideally replace it in the long term.